•An operad in the non-negative integers, where

is a sequence *C*(*j*)*, j>0**, * for which

and
for which *C*(*1*)*=0**. *The first condition simplifies to

III.
Examples of 2-fold operads.

1)
Fibonacci numbers: *0, 1, 1, 2, 3, 5, 8, 13, 21, ….*

2) Counting
numbers: *0,
1, 2, 3, … .*